The purpose of this study is to determine whether the nicotinic receptor antagonist mecamylamine hydrochloride (Inversine) can augment SSRI-refractory major depression symptoms, quality of life and cigarette smoking outcomes. A total of n=60 SSRI-refractory patients who are on stable doses of an SSRI are being recruited into this 8-week double-blind, randomized, placebo-controlled trial.